Fumigants are commonly used to ward to off insects or to provides fragrance/aroma to the atmospheres/environment in dwellings. Most of these articles comprise an active ingredient dispersed in burning material. For instance, if the article is intended to act as a household insecticide, the active ingredient is an appropriate synthetic and/or natural insecticide that is released in the atmosphere and emits fumes which repel insects. Similarly, if the purpose of manufacture is to use the articles as air-freshening devices, the active ingredients are synthetic or natural fragrances or the admixtures thereof that evaporate on burning and emit pleasant fragrances. Such agents, may be for example, sandalwood powder or essential oils obtained from aromatic plants. The commonly used active ingredients in case, the fumigant is to function as a domestic and or outdoor insecticides are (S-2-Methyl-4-oxo-3-(2-propynyl)cyclopent-2-enyl(1)-cis.transchrysanthemate (common name: Prallethrin; brand name: Etoc, product of Sumitomo Chemical Co., Ltd.,), d-allethrin (brand name Pynamin Forte, product of Aventis Crop Science), Esbiothrins (trade name EBT product of Aventis Crop Science), Transfluthrin (common name and product of Bayer, Germany) and/or synthetic pyrethroids or other similar active ingredients combined with burning materials such as coconut shell powder, saw dust, binding agents, starch, etc. Aids that sustain burning of the article for a long period are also added optionally.
U.S. Pat. No. 4,144,318 describes a mosquito coil composition containing 72-83% by weight based on dry ingredients of a carrier selected from sawdust, coconut shell etc 16-26% by weight potato starch, water etc. The prior art is replete with compositions useful as insect repellents or as incense materials.
U.S. Pat. No. 3,819,823 discloses a mosquito coil containing a chrysanthemic acid ester. Another insecticide is disclosed in JP 58096004A2 containing substituted acetic acid ester. Thus, the prior art is replete with instances of insect repellent compositions used in coils. There is very little focus on the shape of the coils.
The earliest insect repellents are spiral coils such as illustrated in Japanese Patent 78027-341. This patent provides spiral coils which are produced from dough compositions of fibrous waste (such as rayon waste, cotton waste, mineral fibres etc).
U.S. Pat. No. 5,657,574 discloses a coiled insect fiumgant having enlarged outer portion for Providing quick coverage of an insect control ingredient in a space that previously resistance and kerosene and peanut shell powder to improve igniting and burning characteristics. This insect fumigant coil comprises radially outward, insect control ingredient-containing region linked to an insect control ingredient-containing inner coil, the inner coil extending radially inward from the radially outward region.
U.S. Pat. No. 4,765,090 describes self-supported mosquito incense formed with a plurality of lower extensions on the bottom surface of the incense coil and a plurality of upper recess portions on the upper surface of the coil wherein each lower extension is projectively corresponding to each upper recess portion, so that each upper coil can be overlapped on each lower coil for its handling or storage, and each coil can stably stand on any place or dish for smooth is burning without the aid of any teeth-supported ash tray.
U.S. Pat. No. 5,447,713 provides a mosquito coil in the form of a spiral which is punched out from a board consisting of wood-chip and/or wood-fiber material.
Another Japanese Patent Application 08168669 dated 10th Jun., 1996 and published on 22, Dec. 1997 discloses a mosquito repellent incense and a device for controlling the combustion time thereof. The application also provides a device for controlling the combustion time capable of freely setting the combustion time. Another problem with this type of coil is that its shape makes the coil prone to breakage and therefore does not lend itself to prolonged use.
GB Patent no 2139498 discloses an insect repellent device comprising a flexible backing sheet onto which is printed an elongated single continuous band or coil of material comprising a mixture of filler and active ingredient.
It is common knowledge that the common spiral coil is not structurally stable and is susceptible to breakage. Another problem associated with spiral coils is that once two or three coils are integrated or coupled as a set, it is quite difficult to separate the member coils without any breakage. Broken fragments of the coil are not preferred as the burning time of these fragments is very limited and difficult to fix at a suitable place for burning. Therefore, structural integrity of the formed coil is very important as the coil, in its final structure, should be provided a shape such that the coil is not prone to breakages on packaging, shipping or use. Therefore, there is a need in a prior art to improve the shape of the existing coils. The prior art at best teaches formation of spiral coils wherein two or three coils are integrated as a set. However, there is no teaching of a set comprising more than 3 coils in a set, such as a set of four coils.
Thus, there is a long felt need to improve the configuration of the coil set to provide improved stability and improved functions. It is to fulfil this long felt need that the applicant has developed novel coiled fumigant set, substantially quadrilateral in shape.